The prior art vehicle-washing device with rolling gravity pressure controlled wrap brushes is disclosed in U.S. Pat. No. 4,769,868 to Pagnanelli et al, incorporated herein by reference. The Pagnanelli et al device has a brush support mechanism which uses track members which are rotatably attached at each end to a frame. The brushes of Pagnanelli et al are slidably supported on the track members by guide members, each guide member having eight rollers mounted on bearings supported by the guide member.
The Pagnanelli et al device suffers from several disadvantages. First, the track members, guide members, rollers and bearings are exposed to air-borne dirt particles, the presence of which tend to reduce the useful life of the device. Second, the Pagnanelli et al device requires sixteen bearings, eight for each of the two guide members, and two additional bearings for each of the two track members. Third, the rollers of Pagnanelli et al are subjected to uneven loading as the brushes pivot back and forth and slide in and out. The result of this uneven loading is uneven wear on the rollers leading to shortened useful life thereof.